Plant-availability of phosphorus in filter substrates derived from small-scale wastewater treatment systems

Abstract Laboratory and greenhouse experiments were conducted on four filter substrates sampled from two constructed subsurface-flow wetlands (WL and WS) and from two infiltration basins (IB1 and IB2), to evaluate the solubility, mobility, and plant-availability of phosphorus (P) accumulated on the substrates during wastewater treatment. The solubility (P concentration in solution) and mobility (net and gross transfer of P ions between solution and substrates in suspension) were determined. The plant-availability of substrate P was assessed in pot experiments after the soil P was labeled with 33P ions. The P accumulated on the substrates ranged from 138 to 276 mg P kg−1 mainly under inorganic form. The P solubility increased up to 500 times and the P sorption capacity decreased significantly after the substrates were used in wastewater treatment. The mobile P varied with time and P concentration in the solution and was closely and highly fitted to the kinetic Freundlich equation. All inorganic P accumulated on substrates was mobile for the WS and WL and about 40% for IB1 and IB2. The P availability to plants did not vary significantly among substrates and with a water-soluble mineral P compound (KH2PO4). It is concluded that the P accumulated on the four substrates was an effective P source for the plants.

[1]  Katarzyna Klimkowska,et al.  Distribution of nutrients and heavy metals in a constructed wetland system , 1999 .

[2]  M. McGechan,et al.  SW—Soil and Water: Sorption of Phosphorus by Soil, Part 1: Principles, Equations and Models , 2002 .

[3]  L. Hylander,et al.  Plant availability of phosphorus sorbed to potential wastewater treatment materials , 2001, Biology and Fertility of Soils.

[4]  C. Morel,et al.  Uptake of phosphate from soils and fertilizers as affected by soil P availability and solubility of phosphorus fertilizers , 1990, Plant and Soil.

[5]  E. Sibbesen,et al.  Phosphorus balance in European agriculture - Status and policy options , 1995 .

[6]  K. Sakadevan,et al.  Phosphate adsorption characteristics of soils, slags and zeolite to be used as substrates in constructed wetland systems , 1998 .

[7]  D. Plénet,et al.  Transfer of phosphorus in soil-plant and soil-solution systems using isotopic labeling and dilution methods. , 2002 .

[8]  P. Veldhoven,et al.  Inorganic and organic phosphate measurements in the nanomolar range. , 1987, Analytical biochemistry.

[9]  T. Krogstad,et al.  Phosphorus sorption and chemical characteristics of lightweight aggregates (LWA)-potential filter media in treatment wetlands , 1997 .

[10]  R. Mann Phosphorus adsorption and desorption characteristics of constructed wetland gravels and steelworks by-products , 1997 .

[11]  J. Morel,et al.  The Fate of Sludge Phosphorus in Soil-Plant Systems , 1996 .

[12]  W. Chardon,et al.  Kinetic Freundlich equation applied to soils with a high residual phosphorus content , 1998 .

[13]  Keith A. Smith,et al.  Physico-chemical screening of phosphate-removing substrates for use in constructed wetland systems , 1999 .

[14]  Hans Brix,et al.  Constructed Wetlands for Wastewater Treatment in Europe , 1998 .

[15]  Jan Vymazal,et al.  The use of sub-surface constructed wetlands for wastewater treatment in the Czech Republic: 10 years experience , 2002 .

[16]  J. Morel,et al.  Soil Isotopically Exchangeable Phosphorus: A Comparison between E and L Values , 1994 .

[17]  S. Larsen The use of P32 in studies on the uptake of phosphorus by plants , 1952, Plant and Soil.

[18]  H. Tiessen Phosphorus in the global environment , 1996 .

[19]  J. Fardeau Le phosphore assimilable des sols : sa représentation par un modèle fonctionnel à plusieurs compartiments , 1993 .

[20]  N. Barrow The description of phosphate adsorption curves , 1978 .

[21]  L. Hylander,et al.  Phosphorus removal from wastewater by filter media: retention and estimated plant availability of sorbed phosphorus , 1998 .

[22]  Tammo S. Steenhuis,et al.  Phosphorus removal by wollastonite: A constructed wetland substrate , 2000 .

[23]  L. Johansson Industrial By-Products and Natural Substrata as Phosphorus Sorbents , 1999 .

[24]  H. Tunney,et al.  Transfer of phosphate ions between soil and solution: perspectives in soil testing. , 2000 .